It is known that insoluble resins, such as Sevelamer, Cholestyramine or Colesevelam, are extremely helpful in treating several pathologies such as hypercholesterolemia (acting as bile acid sequestrants) or hyperphosphataemia (acting as phosphate binding drug) in patients with chronic kidney diseases.
These insoluble resins are all characterized by:                elevated molecular weight;        low or very low solubility, or insolubility;        elevated therapeutically dosage to be administered;        elevated electrostatic charge;        low flowability.        
These characteristics cause serious issues in formulating granular compositions for oral suspension to be filled in a container, such as sachets or cans.
In fact, due to these negative properties, the Health Authorities (such as the Food and Drug Administration) did not authorize to fill containers (sachets or cans) with said insoluble resins over the limits of ±5% of the target weight for each container.
Usually, in order to solve the difficulties related to the low flowability of the granular composition and to the poor uniformity content of the containers, the formulators are obliged to use special dosage equipments.
However, the use of special dosage equipments often do not solve these problems because of the poor wettability and floating on the surface of the liquid—thus remaining immiscible—of the granular composition, caused by the electrostatic charges of said granular composition.
Thus, granular compositions for oral administration comprising such insoluble resins in higher amount for each container and with better flowability and uniformity are needed.
Silica gels are usually used in several industrial applications, and particularly in pharmaceutical field, because of their considerable absorbing power, and their enormous surface area.
Surprisingly, it has been found that the granular compositions comprising insoluble resins, such as Sevelamer, Cholestyramine or Colesevelam, lose all the negative characteristics mentioned-above when a certain amount of silica gel, preferably highly porous silica gel having a mesoporous structure such as Syloid® XDP or Syloid® FP, is added to said granular compositions, thus allowing a better wettability of the insoluble granular composition, and the preparation of reliable dosage forms. In addition, if such silica gels are used in the compositions of the present invention an higher amount of insoluble resins for each container can be used.